Device and method for the quantitative determination of nitrogen oxides in exhaled air and application thereof

ABSTRACT

A volumetric flow of an analyte, including exhaled air, is fed to a gas sensor unit by used of gas flow device, which can include various sensors for the determination of nitrogen oxides. An oxidation catalyst is used when using an NO 2  sensor, which converts nitrogen monoxide to nitrogen dioxide and the gas sensor unit measures the content of nitrogen dioxide. The nitrogen monoxide content is calculated from the nitrogen dioxide content. In order to eliminate cross-sensitivity moisture and ethanol are also measured. The device can be applied to the determination of nitrogen monoxide content of exhaled air.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/DE02/01576 which has an Internationalfiling date of Apr. 30, 2002, which designated the United States ofAmerica and which claims priority on German Patent Application number DE101 21 262.3 filed Apr. 30, 2001, the entire contents of which arehereby incorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to a device and a method for thequantitative measurement of nitrogen oxides, particularly nitrogendioxide, whereby the original content of nitrogen monoxide can becalculated. Furthermore, the invention generally relates to theapplication of this device in conjunction with respiratory tractdiseases, such as asthma.

BACKGROUND OF THE INVENTION

Among 5% of adults and 15 to 20% of children in western industrialnations asthma is one of the most frequently-occurring diseases, andthis tendency is increasing.

Inflammatory conditions of the lower respiratory tracts, such as asthmaor bronchiectasis, are accompanied by an increased nitrogen monoxide(NO) concentration of up to 85 ppb in the exhaled air. A reduction inthe NO concentration is observed when treated with anti-inflammatorymedicines such as corticosteroids. An imminent asthma attack is clearlyindicated earlier by the rise in the NO content of the exhaled air thanin a pulmonary function test. Nitrogen monoxide is thus a preliminarysign of an asthma attack. Measuring this NO in the exhaled air is thusan ideal method of diagnosis, particularly for deciding treatment andchecking the progress of treatment of asthma and other diseasesassociated with inflammation of the lower respiratory tracts.

A precondition for checking the progress of treatment is, however, amobile cost-effective measuring instrument for the quantitativedetection of nitrogen dioxides regardless of location. A constanttelemedical care of chronic diseases would also be of interest.

The accuracy required for the detection of nitrogen oxide in exhaled airin conjunction with the aforementioned diseases is in the area of a fewppb NO. Up to now, this could be achieved only by way of chemoluminescence measurements. The disadvantages are on one hand the size,with a weight of at least 45 kg, and on the other the high cost of sucha chemo luminescence measuring apparatus. Up to now, the use of thisequipment has been limited to clinics and specialized practices.

At present, peak-flow meters are used to check the progress of, forexample, asthma. These are small devices that enable a simple pulmonaryfunction test. In contrast to the complete pulmonary function test, onlythe highest respiration flow level, the forced expiratory value ismeasured. This is created at maximum exhalation. The measurement istaken several times a day. The device is relatively inexpensive.However, it measures only the end result of an asthma attack, i.e. thenarrowing of the airways, and not a preliminary sign of an attack, suchas for example nitrogen monoxide would indicate. Valuable time forpreventive treatment is thus lost.

Further evidence of an inflammatory condition of the lower respiratorytracts can also be gained from the bronchial mucus, the sputum. Ageneral sputum examination is macroscopic, microscopic andbacteriological and is comparatively time consuming. Obtaining mucusfrom children and patients with severe breathing difficulties is eitherimpossible or very difficult.

SUMMARY OF THE INVENTION

An object of an embodiment of the invention is to provide a simplemeasuring system for the quantitative measurement of nitrogen oxidesthat is as independent of location as possible and to provide a methodof operation with the nitrogen monoxide content in the exhaled air beingdetectable during the care of patients with respiratory illnesses.

An embodiment of the invention involves achieving a mobilecost-effective, quantitative measurement of nitrogen oxides in exhaledair by an apparatus that has a device for guiding the volumetric flow ofthe exhaled air in succession to an oxidation catalyst for oxidation ofthe nitrogen monoxide content to nitrogen dioxide, to a gas sensor unitfor detection of nitrogen dioxide, moisture and ethanol and also to aunit for calculating the nitrogen monoxide values from the nitrogendioxide values, with the moisture and ethanol concentrations eliminatingthe cross-sensitivity of the nitrogen oxide measurements. Thecombination of a very precise nitrogen oxide measuring method, withwhich the quantitative measurement of nitrogen oxides in the exhaled airis also possible, with a suitable test setup that guarantees thepreparation of the measured gas mixture together with the calculation ofthe nitrogen monoxide content in the exhaled air, provides acost-effective gas sensor system for detection of the nitrogen monoxidecontent and enables conclusions to be drawn regarding respiratoryillnesses.

The use of a gas sensor operating on the principle of work functionmeasurement for the detection of nitrogen oxide has energy advantages.This enables measurements to be taken with a relatively low heat energyrequirement, which makes the development of a cost-effective sensoreasier. It also enables applications with sensors to be opened up thatbecause of the environment would be required to have a low electricalpower. Furthermore, the use of this measuring principle has theadvantages of a relatively wide range of sensitive materials that arerelatively easy to prepare. Generally, however, gas sensors can be usedthat can detect between 3 and 100 ppb in the target area with asufficiently high resolution. Semi-conducting metal oxide gas sensorscan also particularly be used in this case, or a sensor using theprinciple of work function measurement.

An advantageous embodiment of the invention provides that the volumetricflow of the exhaled air is divided in the apparatus, with a partvolumetric flow being directed via the oxidation catalyst and then tothe nitrogen oxide measurement and another part volumetric flow beingsent directly to the nitrogen oxide measurement. In this way,verification of the nitrogen monoxide in the exhaled air canparticularly be determined without disturbance from nitrogen oxide fromthe ambient air. The actual nitrogen monoxide content of the exhaled aircan be determined without error from the difference in the nitrogendioxide concentration. The volumetric flow is measured usingconventional measuring methods.

Various field effect transistors are known for nitrogen oxide detectionusing the principle of work function measurement, with the gas-sensitivelayer being represented as a gate electrode. This gate electrode can beseparated from the channel area of the field effect transistor by an airgap. A change in the potential between the gate and channel area(ΔV_(G)) is used as the basis for a detecting measuring signal. Hybridflip—chip arrangements of gas sensors that are designed as CMOStransistors are known, for example, from German patent applications No.198 14 857.7 and No. 199 56 806.5. A gas sensor can also be fitted withtwo field effect transistors, the control characteristic of which can bematched by approximately equal air gaps between the channel area andgate electrode and the sensor layers of which can be separately read.German patent application No. 199 56 744.1 describes how the clearancebetween the gate electrode and channel area of a field effect transistorcan be reproducibly represented by extremely precise spacers. In adifferent embodiment the gas-sensitive material is applied in porousform to the channel area or gate.

Cross-sensitivities can be eliminated by combining several individualsensors in a gas sensor unit in the form of various gas-sensitivelayers. One layer must of course be sensitive to the target gas. Furthergas-sensitive layers are designed for the detection of moisture oralcohol. A reference layer is, for example, insensitive. The integrationof different gas-sensitive layers of this kind in a gas sensor unitenables the effects of moisture and alcohol to be eliminated.

To eliminate interference with the measurement due to the effect of thedifference between the exhaled air temperature or measured gastemperature and sensor temperature, it is also necessary to performtemperature compensation by using a second transistor. For the selectivedetection of exhaled gases it is particularly necessary to take accountof the effect of moisture, because the concentration of moisture canrise up to 100% relative air humidity. Furthermore, it is alsorecommended that the concentration of alcohol be taken into accountbecause this component can occur in very high concentrations in theexhaled gas compared to nitrogen oxides.

A layer combination, for example, looks as follows:

target-gas sensitive layer; gas-insensitive reference layer;moisture-sensitive layer; moisture-insensitive reference layer;alcohol-sensitive layer; alcohol-insensitive layer and temperaturesensor, in one unit. This enables interference with the measurement dueto the influence of deviations between the temperature of the exhaledair and the sensor operating temperature, the effects of moisture and ofalcohol contained in the breath to be eliminated.

Gas-sensitive layers for use in an SG-FET (Suspended Gate Field EffectTransistor) can advantageously be porphine pigments, such asphthalocyanines with a central atom of copper or lead. At sensortemperatures between 50° and 120°, nitrogen oxide sensitivities down tothe lower ppb range can be verified. Detection is, as normal, aimed atnitrogen dioxide, with it being possible to calculate nitrogen monoxideusing the method already described.

Other materials suitable for use in gas-sensitive field effecttransistors as gas-sensitive layers for the detection of nitrogen oxide,particularly nitrogen dioxide, are fine crystalline metal oxidesoperated at temperatures between 80° C. and 150° C. In particular thesecan be SnO₂, WO₃, In₂O₃, but salts from the carbonate systems such abarium carbonate or polymers such as polysiloxane are also conceivable.

Gas-sensitive layers of polysiloxanes can also be used for the detectionof ethanol. Moisture is advantageously detected using gas-sensitivelayers of polyamide or polypyrrolidone.

Phthalocyanines are particularly suitable for ΔΦ measurements fordetection of NO₂ gases with central atoms such as copper or lead, butalso the compounds with tin, nickel, cobalt or zinc as the central atom.Phthalocyanine compounds and their derivates, that have no central atom,are particularly sensitive to NO₂;

instead the free binding sites in the porphine ring are saturated byhydrogen atoms, such as in the case of heliogen blue G and aphthalocyanine with phenylether side chains. At sensor temperaturesbetween room temperature and 120° C., NO₂ sensitivities down to thelower ppb range can be verified.

For verification of NO₂ in the lower ppb range, porphyrines andmetalloporphyrines are suitable in addition to the phthalocyaninepigments. These include the metal-free porphyrines such asprotoporphyrine IX sodium salt or metal-containing porphyrines such ascobalt protoporphyrines IX. To improve the response times of thesensors, the sensor layers are used at temperatures from roomtemperature up to 75° C.

An advantage of these investigated materials is that, compared with thephthalocyanines, at relatively low temperatures they have very smallresponse times and a high NO₂ sensitivity. Thus, the sensors can also beoperated at lower heater voltage, thus significantly reducing the powerrequirements of the sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description of preferred embodiments given hereinbelow and theaccompanying drawings, which are given by way of illustration only andthus are not limitative of the present invention, and wherein:

FIG. 1 shows an NO₂ characteristic curve of a sensor with agas-sensitive layer of copper phthalocyanine,

FIG. 2 shows a gas sensor using the principle of work functionmeasurement as a suspended-gate FET.

FIG. 3 shows the construction of a sensor system for determining theconcentration of nitrogen monoxide in the exhaled air with thecorrection of cross-sensitivities, for example from the ambient air.

FIG. 4 shows the principle of conversion of nitrogen monoxide tonitrogen dioxide.

FIG. 5 shows a complete sensor system for determining the concentrationof nitrogen monoxide in exhaled air.

FIG. 6 shows the possibilities of converting a nitrogen monoxidemeasurement for diagnosis, planning therapy and monitoring progress ofasthma sufferers.

FIG. 7 shows a diagram with an NO₂ characteristic curve of heliogen blueG and of a phenylether derivate of an H2 phthalocyanine.

FIG. 8 shows a diagram with an NO₂ characteristic curve ofco-protoporphyrine and one from metal-free protoporphyrine Na-salt.

FIG. 9 shows the construction of a sampling system for use in an asthmasensor.

FIG. 10 shows a further example of a sensor system for determining theNO concentration in exhaled air.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To determine the nitrogen oxide in exhaled air for the detection ofasthma, it must be guaranteed that only the exhaled bronchial air isdetected. Because air exhaled through the nose has a nitrogen oxideconcentration increased by a factor of 1000, the volume of exhaled airto be measured must be precisely defined. This can be achieved byexhaling against a resistance, for example through a valve that opensonly at increased air pressure, so that the soft pallet automaticallycloses and the breath is exhaled only through the mouth and not throughthe nose.

To verify nitrogen monoxide in the exhaled air it is necessary topreclude interference due to nitrogen oxide from the ambient air. To dothis, the volumetric flow of the exhaled air is divided. One part of theexhaled air containing nitrogen is used directly for determining theresidual concentration of NO₂. The second part is oxidized to nitrogendioxide by way of a converter (oxidation catalyzer) and the nitrogendioxide concentration is then measured. The actual nitrogen monoxidecontent of the exhaled air can be precisely determined from thedifference between the concentrations of nitrogen dioxide.

The main advantages of the overall system are that a non-invasive methodof measurement is used. The measurements are repeatable a large numberof times and can thus also be used particularly to monitor the progressof therapy, to diagnose asthma in children, for the early detection ofasthma or for preventive medicinal measures. The system with a gassensor unit presented here is an exhaled gas sensor that is smaller tomanufacture and more cost-effect to use and is therefore also suitablefor use outside clinics and doctors' practices.

FIG. 6 shows the chain of actions for illustration of an applicationscenario. Using asthma as an example, it can be stated that measurementsof nitrogen monoxide concentrations as a key to the diagnosis of theplanning of therapy and monitoring progress make a substantialcontribution to the decision making. Further advantages of thearrangement in accordance with the invention lie in the elimination ofcross-sensitivities or interference to measurements due to nitrogenoxide gases from the ambient air when determining the concentration ofnitrogen monoxide.

Because of the occurrence of nitrous oxides in the ambient air inconcentration ranges relevant to the verification of an asthma illness,the disturbance effects from the ambient air must be eliminated. To dothis, the nitrogen dioxide concentration already present in the exhaledair or that may enter the exhaled air due to sampling errors, must bedirectly determined by means of nitrogen dioxide gas sensors. Inparallel with this, the nitrogen monoxide content in the exhaled air isquantitatively converted to nitrogen dioxide by means of a converter andquantified by a second nitrogen dioxide sensor. The differential signalof these two measurements then provides the amount of nitrogen monoxidein the exhaled air and verification for the assessment of the asthmaillness. The described method is schematically shown in FIG. 3.

FIG. 4 shows a schematic for the conversion of nitrogen monoxide tonitrogen dioxide. To be able to determine the concentration of nitrogenmonoxide in the exhaled air, the nitrogen monoxide content isquantitatively converted to nitrogen dioxide and the concentration isdetermined by way of a nitrogen dioxide sensor. For conversion of themeasured gas, an oxidation agent such as permanganate salts orperchlorate salts is used, and is usually applied to a catalyst supportsuch as zeolite, alumina or silica gel. This catalyst is placed in thegas flow of the exhaled gas so that the nitrogen monoxide contained inthe exhaled air is quantitatively converted to nitrogen dioxide. ThisNO₂ gas is detected by means of highly-sensitive NO₂ gas sensors. TheNO₂ content of the gas corresponds to the NO content of the exhaled air.

The elimination of the cross-sensitivities is accompanied by animprovement in the measuring accuracy. The sensor system forverification of an asthma illness is fitted with at least three sensors.The target gas nitrogen oxide, the humidity and ethanol are detected. Ananalytical circuit and the transmission of the data in a telemedicalnetwork result in particular advantages with regard to the detection andtreatment of asthma.

The determination of the concentration of moisture and the direct signalcorrection with the NO sensor signal is necessary to eliminate thecross-sensitivity of the NO sensor layer to moisture. The determinationof the alcohol concentration in the exhaled air is necessary to assessthe quality of the NO measurement, because alcohol in the exhaled aircan occur up to a level of 1500 ppm and can lead to falsification of theNO detection in the lower ppb range. FIG. 5 shows an example of a sensorsystem for determining the NO concentration in exhaled air. In thiscase, the exhaled air is not passed through a series of differentsensors but is instead divided into different volumetric flows andsupplied to corresponding, different sensors. Various volumetric flowmeasurements are necessary for this, in order to be able to calculateback to the part gas content in the exhaled air. Each step for NOdetection in FIG. 5 contains corresponding functional units forconversion to NO₂ and its detection. Furthermore, by means of a furtherbypass contained in this NO stage, the basic concentration of NO₂contained in the exhaled air, as shown in FIG. 3, can be determined.

A linking of the output signals of the system described by an embodimentof the invention enables asthma monitoring, with the nitrogen monoxidedetection in the exhaled air being used as an essential part. Theassociated advantages are a simple location-independent operation andthe ability to carry out regular reproducible measurements. Thecontinual progress data obtained in this way provides information onfactors that trigger an attack or on systematic incorrect behavior bypatients. Because a change in the condition of the illness is signaledearly in the NO values of the exhaled air, communicating the dataquickly to the doctor providing the treatment enables medication to beadapted in good time, thus leading to a minimization of the amount ofmedication.

FIG. 1 shows a change in the work function relative to the nitrogendioxide content with a gas-sensitive layer of copper-phthalocyanine.FIG. 2 shows the concept of a gas-sensitive field effect transistorfitted with a gas-sensitive layer applied to a gate electrode spacedapart from the channel area. The signal at the gas-sensitive layer isread using the principle of work function measurement or according tothe work function change.

FIGS. 7 and 8 show examples of certain NO sensors withspecifically-chosen NO sensitive substances as a gas-sensitive layer inthe sensor.

The advantages of the embodiments of the invention are revealed inparticular in the application.

The determination of NO in exhaled gases is a non-invasive method ofmeasurement that is particularly suitable for repeated applications,such as monitoring the progress of therapy, the diagnosis of asthma inchildren, the early detection of asthma or for preventive medicalmeasures.

False measurements due to changes in temperatures at sensors or thepresence of moisture can be corrected.

Interference due to high concentration of ethanol can be detected andcorrected. The gas sensor system can be used for any number ofrepeatable measurements of the exhaled air.

The presented gas sensor is used for the manufacture of smaller and morecost-effective respiratory gas sensors and is therefore also suitablefor use outside clinics and doctors' practices.

Construction of a measuring system for determining NO in exhaled air:The measuring system includes a sampling system and a gas sensor system.The sampling system, as shown in FIG. 9 includes a mouthpiece ofbiocompatible material, the NO/NO₂ converter for oxidation and a NO/NO₂scrubber for elimination of NO/NO₂ from the measured gas. This samplingsystem can be flexibly connected to the gas sensor system, for exampleusing threaded unions or plugs and can be renewed after one or moreuses.

With aid of the sampling system, zero air, i.e. air that is free of NOand NO₂, is inhaled before the measurement by way of an NO/NO₂ scrubber.The NO/NO₂ scrubber includes a filter combination of active carbon andaluminum oxide or zeolite, or silica gel or a combination of thesematerials. This NO/NO₂ scrubber is fitted with a one-way valve so thatinhalation is possible only through the NO/NO₂ scrubber and not throughthe converter column. This arrangement prevents NO or NO₂ gas, presentin the ambient air in substantially higher concentrations than in thelungs, being inhaled into the lungs and thus increasing the levels inthe exhaled air.

The exhaled air is blown through a second one-way valve to the NO/NO₂converter and not through the NO/NO₂ scrubber. The converter includespotassium permanganate immobilized on silica gel.

The purpose of the converter is to:

convert the NO gas to NO₂ gas at room temperature and

reduce the moisture in the exhaled gas.

Advantages of embodiments of the invention lie particularly in theapplication:

Air free of NO and NO₂ is inhaled, which indicates that the measurementis free of interference due to ambient air.

Dew formation on the sensor is avoided because silica gel absorbs partof the moisture in the breath.

There is no heater for the converter because oxidation of NO gas to NO₂gas takes place at room temperature.

The replacement of system parts to be renewed, such as a mouthpiece thathas to be renewed for reasons of hygiene or a converter that becomesused up and has to be replaced, is flexible and fast.

The gas sensor measuring system corresponding to FIG. 10 includes asupply for the nitrogen dioxide-containing respiratory gas that is blowninto the gas sensor unit through a changeover valve. In the gas sensorunit there are at least three gas sensors and three reference sensorsfor determining the NO₂ content, the moisture and the ethanol content inthe exhaled air. Furthermore, it contains a temperature sensor fordetermining the gas temperature. Each sensor has a temperature regulatorto set the temperature of the gas sensors. The gas sensor unit isfollowed by a gas outlet with a micropump. In addition to the gas inletfor the nitrogen dioxide-containing gas of the respiratory air, there isalso a second gas inlet fitted with a filter system (activecarbon+aluminum oxide/zeolite/silica gel combination). This filtersystem produces zero air and, after the gas has been measured, clearsthe measuring chamber/gas sensor unit and supply channels of NO₂ gas andother interfering gases and regenerates the gas sensors. With the aid ofthe micropump at the gas outlet and the changeover valve before themeasuring chamber, the zero air, air free of NO/NO₂, is drawn in and thecomplete sensor system is regenerated and restored to the measuringmode.

The gas sensor system is also fitted with an analytical circuit to readthe signals from the gas sensors and reference sensors, perform moisturecorrection, calculate the gas concentration and determine the NOconcentration. The NO content is displayed on a digital display on themeasuring system and is available for telemedical data transmission.

FIG. 9 particularly shows the improvement in the measuring arrangementby installing the converting column and arranging a zero air supply atthe mouthpiece.

Exemplary embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. Device for quantitative measurement of nitrogen monoxide in exhaledair, comprising: a gas sensor unit including at least one gas sensorbased on a principle of work function measurement, the at least one gassensor including a first-type gas-sensitive layer containing a porphinepigment, an oxidation catalyst for oxidation of nitrogen monoxide tonitrogen dioxide, and at least one further sensor for the detection ofat least one of moisture and ethanol for elimination ofcross-sensitivities, wherein the device is configured to measure thenitrogen monoxide, in the exhaled air of an individual, using the gassensor unit.
 2. Device according to claim 1, further comprising a fieldeffect transistor including the first-type gas-sensitive layer, thefield effect transistor being adapted to read the work function and thefirst-type gas-sensitive layer being in the form of a porous materialdeposited on a channel area of the field effect transistor.
 3. Deviceaccording to claim 1, wherein the first-type gas-sensitive layer detectsnitrogen oxide, the porphine pigment being a gas-sensitive material. 4.Device according to claim 3, wherein the porphine pigment is at leastone of a phthalocyanine, a derivate of a phthalocyanine with the centralatom being at least one of copper, lead, tin, nickel, cobalt, or zinc,and a phthalocyanine without a central atom whose free binding sites inthe porphine ring are saturated by hydrogen atoms.
 5. Device accordingto claim 4, wherein the phthalocyanine without the central atom is atleast one of heliogen blue G and a phthalocyanine with phenylether sidechains.
 6. Device according to claim 1, wherein the device fordetermining the nitrogen monoxide in exhaled air is mobile.
 7. Deviceaccording to claim 1, further comprising: a gas flow device for thesupply of the volumetric flow of at least one of nitrogen dioxide andnitrogen dioxide and at least one component of at least one of moisture,ethanol and temperature.
 8. Device according to claim 7, wherein thevolumetric flow of the exhaled air is divided in the gas flow deviceinto a part volumetric flow via the oxidation catalyst for oxidation ofnitrogen monoxide to nitrogen dioxide and then to the gas sensor unitfor measurement of the nitrogen dioxide concentration, and into afurther part volumetric flow supplied directly to a further nitrogendioxide gas sensor for determining the nitrogen dioxide concentration,wherein the nitrogen monoxide concentration of the exhaled air iscalculatable by using the individual nitrogen dioxide concentrations. 9.Device according to claim 7, wherein the complete volumetric flow of theexhaled air in the gas flow device is supplied through the oxidationcatalyst for oxidation of nitrogen monoxide to nitrogen dioxide and thento a gas sensor unit for measurement of the nitrogen dioxideconcentration, wherein the nitrogen monoxide concentration of theexhaled air is calculatable by using the nitrogen dioxide concentration.10. Device according to claim 8, wherein at least one substance from thegroup of at least one of permanganate salts and perchlorate salts isapplied to a support including at least one of zeolite, aluminum oxideand silica gel as a material for the oxidation catalyst.
 11. Deviceaccording to claim 1, wherein sensor signals processed in an analyticalcircuit are supplied to a data network.
 12. Device according to claim 2,wherein the first-type gas-sensitive layer detects nitrogen oxide, theporphine pigment being a gas-sensitive material.
 13. Device according toclaim 12, wherein the porphine pigment is at least one of aphthalocyanine, a derivate of a phthalocyanine with the central atombeing at least one of copper, lead, tin, nickel, cobalt, or zinc, and aphthalocyanine without a central atom whose free binding sites in theporphine ring are saturated by hydrogen atoms.
 14. Device according toclaim 13, wherein the phthalocyanine without the central atom is atleast one of heliogen blue G and a phthalocyanine with phenylether sidechains.
 15. Device according to claim 9, wherein at least one substancefrom the group of at least one of permanganate salts and perchloratesalts is applied to a support including at least one of zeolite,aluminum oxide and silica gel as the material for an oxidation catalyst.16. Device according to claim 1, wherein the at least one gas sensorincludes: a hybrid field effect transistor including the first-typegas-sensitive layer, the first-type gas-sensitive layer beingrepresented by a gate electrode spaced apart from a channel area used toread the work function.
 17. Device according to claim 16, wherein thehybrid field effect transistor is of a hybrid flip-chip construction.18. Device according to claim 16, wherein the at least one furthersensor includes at least one second-type gas-sensitive layer formed of amaterial that includes at least one of polyamides and polypyrrolidonesfor the detection of moisture or includes polysiloxanes for thedetection of ethanol.
 19. Device according to claim 16, wherein thehybrid field effect transistor includes a second-type gas-sensitivelayer in the form of porous material deposited on the channel area,wherein the hybrid field effect transistor is adapted to read the workfunction.
 20. Device according to claim 16, wherein the first-typegas-sensitive layer detects nitrogen oxide, the porphine pigment being agas-sensitive material.
 21. Device according to claim 20, wherein theporphine pigment is at least one of a phthalocyanine, a derivate of aphthalocyanine with the central atom being at least one of copper, lead,tin, nickel, cobalt, or zinc, and a phthalocyanine without a centralatom whose free binding sites in the porphine ring are saturated byhydrogen atoms.
 22. Device according to claim 21, wherein thephthalocyanine without a central atom is at least one of heliogen blue Gand a phthalocyanine with phenylether side chains.
 23. Device accordingto claim 1, further comprising: a hybrid field effect transistorincluding a second-type gas-sensitive layer represented by a gateelectrode spaced apart from a channel area used to read the workfunction.
 24. Device according to claim 23, wherein the hybrid fieldeffect transistor is of a hybrid flip-chip construction.
 25. Deviceaccording to claim 23, wherein the at least one further sensor includesat least one third-type gas-sensitive layer formed of a material thatincludes at least one of polyamides and polypyrrolidones for thedetection of moisture or includes polysiloxanes for the detection ofethanol.
 26. Device according to claim 23, further comprising: a fieldeffect transistor including the first-type gas-sensitive layer, thefield effect transistor being adapted to read the work function and thefirst-type gas-sensitive layer being in the form of porous materialdeposited on the channel area.
 27. Device according to claim 23, whereinthe at least one first-type gas-sensitive layer detects nitrogen oxide,the porphine pigment being a gas-sensitive material.
 28. Deviceaccording to claim 27, wherein the porphine pigment is at least one of aphthalocyanine, a derivate of a phthalocyanine with the central atombeing at least one of copper, lead, tin, nickel, cobalt, or zinc, and aphthalocyanine without a central atom whose free binding sites in theporphine ring are saturated by hydrogen atoms.
 29. Device according toclaim 28, wherein the phthalocyanine without a central atom is at leastone of heliogen blue G and a phthalocyanine with phenylether sidechains.
 30. Device according to claim 2, wherein the at least onefurther sensor includes a second-type gas-sensitive layer, wherein thesecond-type gas-sensitive layer is formed of a material that detectsmoisture and includes at least one of polyamides and polypyrrolidonesand includes polysiloxanes for the detection of ethanol.
 31. Deviceaccording to claim 2, wherein the at least one gas sensor includes thefield effect transistor, and the field effect transistor has a hybridflip-chip construction.